This invention relates generally to fiber optic communication systems and, more particularly, to Sagnac interferometer based fiber optic systems that utilize counterpropagating light paths to form a fiber optic communications loop. Alarm systems, which are adapted to detect changes in the optical characteristics in the loop, including changes in the optical power or optical frequency, are used to avoid the risk of compromising data and to alert users to an intrusion attempt.
The need for high bandwidth secure communication systems that are amenable to use in networks and which minimize the need for encryption is becoming increasingly acute. Long-term trends for very high bandwidth sensors, computers, and multichannel video display capabilities will dictate the specific designs utilized in serving this type of technology. The advent of fiber optics has opened up a new era where very high speed, low cost telecommunication is possible.